Highlighter pen



FIG. 1 is a perspective view of a highlighter pen showing my new design;

FIG. 2 is a front view thereof; the rear view is omitted since it is a mirror view of the front view;

FIG. 3 is a right side view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a top plan view thereof;

FIG. 6 is a bottom plan view thereof; and,

FIG. 7 is an exploded view thereof.

A rear view is omitted since it is a mirror of the front view. 

I claim the ornamental design for a highlighter pen, as shown and described. 